[mythtv-commits] Ticket #10110: mythtranscode --mpeg2 Inserts Vertical-Line Artifacts

MythTV noreply at mythtv.org
Wed Oct 19 10:13:02 UTC 2011

#10110: mythtranscode --mpeg2 Inserts Vertical-Line Artifacts
 Reporter:  Dave Sp <davespmyth@…>   |           Type:  Bug Report -
   Status:  new                      |  General
Milestone:  unknown                  |       Priority:  minor
  Version:  0.24-fixes               |      Component:  MythTV -
 Keywords:                           |  Mythtranscode
                                     |       Severity:  medium
                                     |  Ticket locked:  0
 I use "mythtranscode --mpeg2 --honorcutlist ..." from the command line to
 create a cut version of a recording.

 When I play the result, vertical purple lines show up every 50 seconds.
 Each burst of purple lines lasts 20 frames, give or take a few.

 (If I don't use the "--mpeg2" option, the result has no purple lines, but
 it takes a lot longer to generate the file, and at the end of a long
 recording the audio gets out of sync.)

 The output from "mythtranscode --mpeg ..." has those purple vertical lines
 when played in mythvideo, mplayer, and vlc.

 I re-ran "mythtranscode --mpeg ..." with "-v all".  It seems the purple
 lines coincide with the debug lines "Inserting 0 I-Frames after #....".

 Each time MPEG2fixup::Start had to call InsertFrame, deltaPTS was either
 1201 or 1202, and ptsIncrement was 1501.  If I prevent calling InsertFrame
 under those conditions, the end result has no vertical line artifacts
 every 50 seconds, but then handbrake-cli spits out hundreds of "sync:
 video time didn't advance" messages and mythvideo complains of lots of A/V
 sync issues and doesn't show the time properly.

 So it seems InsertFrame needs to be called when deltaPTS is either 1201 or
 1202 and ptsIncrement is 1501.  Is MPEG2fixup::InsertFrame supposed to
 insert a duplicate of the previous frame, or is it inserting a frame with
 no data (resulting in those vertical-line artifacts)?

 An example is attached of what those lines look like.

Ticket URL: <http://code.mythtv.org/trac/ticket/10110>
MythTV <http://code.mythtv.org/trac>
MythTV Media Center

More information about the mythtv-commits mailing list